Scientists have put a new turn on the theory of how the Moon was created.

It has long been thought that the lunar body resulted from an impact between the early Earth and another planet-sized object 4.5 billion years ago but this theory predicts Earth and its satellite should have a quite different chemical make-up - and the data shows in fact they are very similar. Now, new modelling reveals that if the Earth had a much faster spin before the impact, the theory fits the chemistry.

It is one idea to fix the composition conundrum explored in two papers published this week by the journal Science. The giant impact hypothesis was first posited in the 1970s. It holds that the Moon formed from the debris kicked into orbit by the collision of a smaller proto-planet with the infant Earth but the early models indicated that much of this debris would have originated from the impactor, whose composition would most probably have differed substantially from that of Earth.

This is not reflected in the analysis of Earth and Moon rocks – for example, their oxygen isotope, or atom type, compositions are identical.

So the moon has the same Oxygen isotope ratios as which part of the Earth? They differ substantially depending on where in the Earth you look. And the moon is a differentiated body, so its isotope distribution would have gone through a similar differentiation to that of the Earth post-formation. We only have samples of its crust.

All those theoretical words and numbers to remember and understand. It's much easier to sit in my pew and be told god created a lesser light to rule the night (except during a new moon when it doesn't -- pastor says we're not to question that).

Logged

There is no opinion so absurd that a preacher could not express it.-- Bernie Katz